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//
//   http://www.apache.org/licenses/LICENSE-2.0
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use std::collections::HashSet;

use crate::error::Result;
use crate::physical_plan::udaf::AggregateUDF;
use crate::physical_plan::udf::ScalarUDF;

/// A registry knows how to build logical expressions out of user-defined function' names
pub trait FunctionRegistry {
    /// Set of all available udfs.
    fn udfs(&self) -> HashSet<String>;

    /// Returns a reference to the udf named `name`.
    fn udf(&self, name: &str) -> Result<&ScalarUDF>;

    /// Returns a reference to the udaf named `name`.
    fn udaf(&self, name: &str) -> Result<&AggregateUDF>;
}
